


Good Boy

by Music_Junkie



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell, Alternate Universe - Underswap, Ecto-Genitalia, Explicit Sexual Content, Fluff and Smut, Fontcest, Honey Mustard - Freeform, M/M, Oral Sex, Skeleton Sex, Vaginal Fingering, honeymustard - Freeform
Language: English
Status: Completed
Published: 2016-05-09
Updated: 2016-05-09
Packaged: 2018-06-07 08:38:52
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 673
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6797026
Author URL: https://archiveofourown.org/users/Music_Junkie/pseuds/Music_Junkie
Summary: <blockquote class="userstuff">
              <p>Underfell!Sans giving Underswap!Papyrus a blowjob. Basically an excuse to write honeymustard, which is all kinds of adorable and I love it. There's a brief mention of Underfell!Papyrus, but he doesn't make an appearance. That's it, no plot whatsoever.</p>
            </blockquote>





	Good Boy

**Author's Note:**

  * For [0neType](https://archiveofourown.org/users/0neType/gifts).



> This is based off a drawing by 0netype over on tumblr, right over here: http://0netype.tumblr.com/post/144019844547/my-fave-hc-is-that-sans-is-so-good-at-what-he-does
> 
> Picture is very nsfw, along with this fic. This is also shameless smut, and while I think my writing has improved, I am admittedly very rusty with sex scenes. I've mostly been writing fluff, okay. First post to this account, and it's porn. Go me. XD And yes, I know the title is unoriginal, I've never been good with those.

 

You’re really good with your mouth. You’ve been told this over and over, and it’s at least one thing you  _ know _ you can do. Sure, you’ve fucked and been fucked, but it was mostly for relief, never really pleasure.    
  
(At least not yours, anyway.)   
  
So it’s easy to sink to your knees like a good boy, unzip Stretch’s pants, and pull out the bright orange erection.    
  
You start slow, using your hands at first and getting him nice and slick. Once your hands move easier, you take him into your mouth.    
  
This isn’t the first time you’ve done this with him, and probably not the last, but in a way, it’s gratifying to hear him encourage you.    
  
You tilt your head just so, raising an eyebrow ridge, and pull back so that he slips out of your mouth, leaving a smear of pre-cum down your chin.    
  
“Doing okay up there?”    
  
Stretch rests a hand on your skull. “More than okay.”    
  
You take him back in your mouth, and tentatively rest a hand on his thigh. It’s still a little odd to not be bound, to not have Boss yanking on that damned leash at the same time. At least your jacket collar is staying clean.    
  
_ (Not fast enough, not good enough, gotta keep going ‘til Boss is done.)  _ __  
__  
Stretch’s legs are trembling, which you  _ know  _ means you’re doing it right, because he’s going just that little bit thicker, a little harder, and the fizzy, almost sweet taste of his magic gets stronger at the back of your throat. He’s stretching your mouth just that bit more, and it’s a pleasant sensation.    
  
Stretch is always careful to never push himself deeper, like he’s afraid to choke you or something. It’s kind of nice, and you reward him by taking as much as you can, blinking away tears at the corners of your eye sockets. Long phalanges stroke your skull as you do so, gasps and groans and swears urging you on.    
  
You swirl your tongue around the tip, pressing gently at the underside, and that usually does the trick. But he still hasn’t come yet, and, confused, you look up the best you can manage. His expression is dazed, happy, and maybe he was just waiting for something, because then he’s coming, filling your mouth, and you reflexively swallow as fast as you can.    
  
You don’t mind the taste, really. It’s not sour like Boss’, and Stretch doesn’t mind if you can’t swallow it all.  __   
  
Once he’s finished, you sit back on your heels, and wipe at your mouth.    
  
“Good boy.” Stretch motions for you to come closer.    
  
You beam proudly, and climb into his lap. He presses his teeth against the top of your skull, and against your cheeks, and then your mouth.   
  
“I really enjoyed that.”   
  
Well, no shit. You can feel his taste still lingering at the back of your throat, and your hands are still sticky.   
  
“Good boys get a reward.”  Before you can protest, he’s slipped a hand under your shorts, then stops, watching you. Waiting for permission, you realize. You nod, and he  begins slowly rubbing at the clit to the vagina you’d formed while sucking him off. That always feels odd, you’re not used to having someone else return the favor, you usually just take care of it yourself later, and you usually don’t form a vagina to boot.    
  
_ (Not Boss’ responsibility, after all. But this is not Boss and that’s a reward in itself.)  _   
  
“Hng!”    
  
“Too fast?”   
  
“...n-no.”    
  
“Alright.”    
  
You’d expect his phalanges to be cold, but they’re surprisingly warm when he pushes them inside you, and it’s a good feeling, you were good and you earned this.    
  
He rubs your spine and works you open, thumb rubbing at your clit and-  _ oh fuck that’s a really sensitive area- _ you push against him. He takes the hint, goes a little faster, and  _ oh  _ **_fuck_ ** _ - _ __  
__  
You clamp down around his fingers, and you bury your face in his shoulder, shaking.    
  
Okay, you were  __ definitely a good boy. 


End file.
